1. Field
The present disclosure relates to 3-dimensional (3D) image acquisition apparatuses and methods of calculating depth information in the 3D image acquisition apparatuses.
2. Description of the Related Art
Recently, the importance of 3-dimensional (3D) content is increasing with the development and the increase in demand of 3D display devices for displaying images having depth perception. Accordingly, there is research being conducted into 3D image acquisition apparatuses, such as a 3D camera by which a user personally creates 3D content. Such a 3D camera acquires depth information in addition to existing 2D color image information in one capture.
Depth information regarding distances between surfaces of a subject and a 3D camera may be acquired using a stereo vision method using two cameras or a triangulation method using structured light and a camera. However, since the accuracy of depth information in these methods rapidly decreases as a distance to a subject increases and these methods depend on a surface state of the subject, it is difficult to acquire accurate depth information.
To improve this problem, a Time-of-Flight (TOF) method has been introduced. The TOF method is a method of measuring a light beam's flight time until the light reflected from a subject is received by a light-receiving unit after an illumination light is projected to the subject. According to the TOF method, light of a predetermined wavelength (e.g., Near Infrared (NIR) light of 850 nm) is irradiated to a subject by using an illumination optical system including a Light-Emitting Diode (LED) or a Laser Diode (LD). A light having the same wavelength is reflected from the subject and is received by a light-receiving unit. Thereafter, a series of processing processes for calculating depth information are performed. Various TOF technologies are introduced according to the series of processing processes.
In the TOF method described above, depth information is calculated by assuming an ideal environment without noise. However, when a 3D camera is used, ambient light, such as illumination in an indoor environment and sunlight in an outdoor environment, always exists in the surroundings. The ambient light is incident to the 3D camera and becomes noise in a process of calculating depth information.
Accordingly, it is necessary to reduce ambient light causing noise in the process of calculating depth information.